Compositions composed of a reaction mixture of an aminoalkylalkoxysilane and an epoxyalkylalkoxysilane (see Japanese Patent Publications 52-8854, 55-41702, and 7-113083), and compositions composed of a cyclic aminoalkylsilane (see Japanese Patent Publication 5-32397) have been proposed as adhesion promoters which enhance the adhesion of curable silicone compositions. However, these adhesion promoters were not capable of imparting sufficient adhesion to a curable silicone composition.
Meanwhile, there are known silatrane compounds expressed by the following formula, in which R is a methyl group, phenyl group, methoxy group, or ethoxy group, but good adhesion was still not exhibited when one of these silatrane compounds was added to a curable silicone composition. ##STR2##